Gregg ash tree named ‘Libby Davidson’

ABSTRACT

A new and distinct Fraxinus greggii tree named ‘Libby Davidson’ is characterized by unusually large, dark green leaves, improved growth rate, improved cold hardiness and is more evergreen than other available Gregg ash.

Latin name: Fraxinus greggii.

Varietal denomination: ‘Libby Davidson’.

INTRODUCTION

The genus Fraxinus, commonly known as ash trees (or shrubs) belongs tothe olive family, Oleaceae, consisting of somewhere in the neighborhoodof 45-65 species distributed worldwide in the continents of NorthAmerica, Asia and Europe. Many species of ash are useful for their woodproducts, as well as for use in landscape plantings. The SectionPauciflorae (E. Wallander) contains about 5 species (Some possiblesynonymies are still unresolved.) native to arid and semiarid regions ofthe Southwestern United States, Mexico and parts of Central America. Allthe Pauciflorae are shrubs or small trees. The leaves are small andcoriaceous with winged rachi. The flowers are apetalous and windpollinated. Fraxinus greggii, Gregg Ash, is found primarily along theRio Grande Valley of Southern New Mexico and Texas. Another disjunctdistribution is reported from southern Chihuahua and Coahuila south toSan Luis Potosi. Gregg Ash has been widely grown as a large landscapeshrub or small tree in the Southwestern United States. The plantseventually grow to about 20 feet tall×20 feet wide in the landscapewithout pruning. The plants have fairly thin branches and can be hedged.Gregg Ash is generally considered to be low-moderate in water use andfairly slow in growth, generally around 1-1.5 feet per year. The plantsare evergreen.

BACKGROUND OF THE INVENTION

Wild Gregg Ash, though attractive in the landscape and droughtresistant, presents some problems to the nursery industry, as the growthrate, adaptability, color, growth form and leaves vary widely. Thiscreates a nonuniform appearance in mass plantings, parking lots and soon. Additionally, perhaps 20% of wild seedlings grow poorly and must bediscarded.

The present invention relates to a new and distinct cultivar of Fraxinusgreggii. The cultivar originated as a seedling in a 2006 growout ofFraxinus greggii seeds gathered from existing nursery plants. About 500seedlings were grown in a cultivated area near Sahuarita, Ariz. Of theseseedlings, one plant proved to be faster growing, with larger and darkergreen leaves than the other seedlings. This cultivar is evergreen andhas not exhibited any frost damage in 10 years of growth at theSahuarita location and is the object of this application.

SUMMARY OF THE INVENTION

Among the features that distinguish the new Fraxinus greggii cultivarfrom all other available and commercial varieties of Gregg Ash known tothe inventor are the following combination of characteristics: Fastgrowth for the species; larger, darker green leaves than typical for thespecies; better frost hardiness (at least 10° F. without defoliation)than typical for the species; improved evergreen tendency for thespecies; and ultimately a larger mature plant size than is typical forFraxinus greggii.

The propagation procedure is as follows: Young hardwood cuttings areprepared from the terminal one foot of branches near the end of summer.These are further cut into 4″ long×2-3 mm thick pieces with the lowernodes deleafed, then placed into a 5:1 solution (water:rooting compound)of DIP'N GRO™ for 15 seconds, followed by planting in trays filled withJIFFY™ PREFORMA™. Trays of cuttings are moved to a fog propagation houselocated at a commercial nursery near Sahuarita, Ariz., maintained at85-90% relative humidity and temperatures varying from 65-85° F.Cuttings root in about 8 weeks.

The foregoing characteristics and distinctions come true to form and areestablished and transmitted through succeeding asexual propagations. Thepresent invention has not been evaluated under all possibleenvironmental conditions, such that the phenotype may vary withvariations in environment without a change in the genotype of the plant.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying photographs illustrate Fraxinus greggii “LibbyDavidson’ growing near Sahuarita, Ariz., depicted in color as nearlycorrect as it is possible to make in a color illustration of thecharacter.

FIG. 1 shows Fraxinus greggii ‘Libby Davidson’ growing near Sahuarita,Ariz. at age 10.

FIG. 2 shows the main trunk of the tree illustrated in FIG. 1.

FIG. 3 shows the first branch above the trunk illustrated in FIG. 2.

FIG. 4 shows young leaves of Fraxinus greggii ‘Libby Davidson’.

FIG. 5 shows mature leaves of Fraxinus greggii ‘Libby Davidson’.

FIG. 6 shows an inflorescence of Fraxinus greggii ‘Libby Davidson’

DETAILED PLANT DESRIPTION

The following is a detailed description of the new Fraxinus greggii‘Libby Davidson’. The specimen described is a 10 year old plant growingunder irrigation near Sahuarita, Ariz. The included color descriptionsare based upon the 5^(th) edition R.H.S. Colour Chart. Color names otherthan common usage are as listed in COLOR Universal Language andDictionary of Names, by Kenneth L. Kelly and Deane B. Judd; NationalBureau of Standards special publication 440. Washington, D.C.: U.S.Department of Commerce, National Bureau of Standards, December 1976.

-   Form: A multitrunked, small, evergreen tree measuring about 18 ft    tall×20 ft wide at age 10.-   Trunk: About 6 inches in caliper at the minimum diameter zone    between the root swell and first branching (about 8 inches above    ground level), bark flakey to somewhat platy, color N187C, with    younger bark in cracks and under flakes closest to color 161D.-   Branch angle: Between about 40° and 75°.-   Stems: Young, but mature stems, cylindrical, 2-3 mm in diameter,    color N187C, finely and obscurely puberulous with scattered    lenticels; these lenticels colored N170D, more or less elongated    longitudinally and rising slightly above the stem surface, from 0.4    mm wide×0.4 mm long to 0.4 mm wide×1 mm long. Internodes vary from 4    to 16 mm in length. Dormant buds 1 mm wide×1 mm long, ovoid,    laterally compressed, very finely puberulent, color 164D. Bud scales    not discernable. By the time the stem diameter reaches about 1 inch,    the bark surface becomes finely elongated reticulate color N187C,    the reticulum slightly raised above the general surface. The    lenticels (color N187D) at this stage tend to cluster in small    groups parallel to the stem axis, varying from 0.4 mm×0.4 mm to 2    mm×1.6 mm, mostly oriented perpendicular to the axis. Older mature    bark eventually becoming flakey and somewhat platy, color N187C.    Newly forming bark in cracks and under flakes closest to color 161D.-   Leaves: Evergreen, opposite leaf arrangement, leaves odd pinnately    compound, overall shape roughly ovate; young leaves mealy with    sparse puberulent hairs, all deciduous by maturity, ultimately    glabrous, somewhat coriaceous and lustrous; leaflets 1-7, mostly 5,    the terminal leaflet larger than the laterals; leaflets    oblanceolate, obscurely and irregularly toothed; apex of leaflets    elliptical, rounded, acute; leaflet bases acuminate. Color of new    leaves 143A adaxially, 143C abaxially. Mature leaves color N137A    adaxially and 138B abaxially.-   Leaf measurements and further details: Leaves 40-79 mm long×18-35 mm    wide. Petioles 13-23 mm long, 1 mm wide×1 mm thick, flattened    adaxially, rounded abaxially; slightly winged; adaxial surface    basally 143B grading to 143C terminally; abaxial surface of petiole    colored as the leaves (138B). Leaf rachis, color 139C, first segment    14-16 mm long, 1 mm wide, 0.75 mm thick with a depressed central    longitudinal vein, which is colored 139D. Abaxial color same as    leaves, color 138B. Terminal leaflets measure from 31-42 mm long×6-9    mm wide. Lateral leaflets measure from 18-26 mm long×5-6 mm wide.-   Reproductive structures: Inflorescences axillary, opposite, and    paniculate with 1-7 branches each, comprised of 5-30 flowers per    inflorescence, flowers hermaphroditic. Inflorescences are 7-15 mm    wide by 7-25 mm long, spreading and somewhat cascading. Peduncles    measure 1 mm thick×1 mm long, terete, with a mealy surface. The base    color is 143A, the flakes of the mealy portion 161A. Inflorescence    bracts are paired (opposite) oblong/lanceolate in shape, finely    sericeous abaxially, color 161A and 1.5-3 mm long×1 mm wide.    Interior of bracts are glabrous, color 151A. Floral bracts appear    similar to inflorescence bracts, but of smaller size with somewhat    reduced pubescence, measuring 1-1.5 mm long×0.5-0.75 mm wide.    Flowers are comprised of 4 sepals fused at the base, without petals,    2 exserted, basifixed stamens and one pistil with 2 stigma lobes.    Pedicels measure 2-3 mm long×0.5 mm thick, terete, color 144A with    scattered wooly hairs. The cup shaped calyx (measuring 1 mm long×1    mm thick) is comprised of 4 sepals; fused at the base, ovate in    shape, 1 mm wide×1 mm long, color 145A. Sepal exterior is covered    with scattered wooly hairs, tufted at the apex of the sepal and    appearing ciliate in casual view. Sepal interior is glabrous. The    corolla is absent. Flowers have two opposing exserted stamens    attached to the receptacle, each as follows: Anthers are 2 mm long×1    mm thick, ovate in shape; color varying from 59A to 59C and    sometimes grading to 145B to 145C basally. Filament at anthesis    measures 1.3 mm long×0.3 mm wide, more or less terete, color 157A.    Anthers dehisce longitudinally on 2 lines. Post dehiscence the    anther color dries to 187A. Pollen is produced, color 158A. The    ovary is superior, with one ovule, 0.3 mm long×0.3 mm thick at    anthesis, glabrous, color 145A. The ovary becomes somewhat    flattened, 3 ribbed and ovate in shape following pollination. The    style measures 0.5 mm long×0.5 mm thick at anthesis, terete,    glabrous, color 145A. The stigma is two lobed, the lobes parallel to    slightly spreading, roughly oblong in shape, 0.66 mm long×0.33 mm    thick at anthesis, terete, color 151A. The stigma darkens to 187B    following pollination. No fruits or seeds have been produced in 10    years of growth at the Sahuarita, Ariz. location. The reasons for    this are unknown, as the plant seems to produce healthy flowers and    pollen. It is speculated that the species may be self-incompatible    and since no other blooming plants are growing nearby, no fruit is    set.-   Diseases and pests: None observed.

COMPARISONS TO RELATED FRAXINUS

No selected varieties of Fraxinus greggii are known to the inventor.Compared to seed grown Gregg ash, ‘Libby Davidson’ has improved coldhardiness, evergreen tendency with a faster growth rate and larger,darker green leaves. As a clonally reproduced plant, Fraxinus greggii‘Libby Davidson’ avoids the crippled plants normally found amongseedling Gregg ash and is uniform in growth and form.

I claim:
 1. A new and distinct Fraxinus greggii plant substantially asdescribed and illustrated herein.